1. Field of the Invention
The present invention relates to a method for accomplishing a requested operation selectively based upon features of other equipment connected through a digital communication line.
2. Description of the Related Art
FIG. 1 shows an example of several electric home appliances connected to each other through a digital interface line such as the IEEE 1394. The electric home appliances connected to each other are a digital versatile disk (DVD) player 100 for reproducing high-quality digital video and/or audio data from an optical disk, a digital video cassette recorder (VCR) 300 for recording/reproducing high-quality digital video and audio data to/from a magnetic recording medium such as a digital video tape, a set top box (STB) 400 for receiving RF broadcast signals, extracting data streams of a selected program from the broadcast signals, and transmitting them to an appropriate equipment, a digital TV 200 for presenting the high-quality video pictures and sounds after decoding received data from a digital satellite broadcast, the DVD player 100, or the digital VCR 300, and a digital audio equipment 500 for outputting high-quality sounds after decoding received digital audio data streams.
The DVD player 100 connected through the IEEE 1394 standard uses a DVD as a medium.
The DVD recording medium will be popularized as a multi-functional disk recording medium since the standard for a DVD recording medium has been rapidly developed among related companies. Therefore, the DVD player will be widely used, and a digital video/audio presenting equipment capable of providing high-quality video pictures and sounds, for example, a digital TV will be also popularized in the near future.
Accordingly, a method using a DVD player or a DVD recorder in connection with a digital TV as shown FIG. 1 is expected to be rapidly increased. The connection standard between electric home appliances such as a DVD recorder, a digital TV, and so on is sure to be IEEE 1394.
The DVD player 100 processes digital data stream  streams of MPEG format, especially a program stream (referred as ‘PS’ hereinafter) differently depending upon whether the data stream contains a presentation data or a navigation data. The presentation data is processed to yield video and audio, and the navigation data is used for controlling a data reproducing operation of a DVD player.
Contrary to the DVD player 100, the digital TV 200 processes digital data streams of MPEG format organized with transport streams (referred as ‘TS’ hereinafter) into presentation data, and converts them into video and audio signals. Accordingly, the DVD player 100 should convert PS into TS before transmission, or the digital TV 200 should convert received PS into TS before signal processing.
The difference between PS and TS is as follows.
The PS consists of several packs and each pack consists of packetized elementary stream (PES) packets containing digitized video, audio, and additional information data. A PES packet can contain data whose size is variable so that the size of a PES packet may not be the same all the time.
On the contrary, the TS consists of transport packets and each packet has a fixed length of 188 bytes including its packet header.
Accordingly, when converting PS into TS, each PES packet of PS should be divided into packets of TS sequentially and necessary header information is added to each divided TS packet at that time. Because a PES packet is divided into multiple TS packets, a remaining area of the last TS packet is stuffed with null data after writing all data of a PES packet in the multiple TS packets.
The digital TV 200 can output high-quality video pictures and sounds by decoding the digital data streams transmitted from the DVD player 100 through the above format-converting process.
The operation such as a disk reproduction of the DVD player 100 can be controlled remotely through the digital TV 200 connected via the IEEE 1394 standard, or directly through key commands on a front panel or a remote controller.
The DVD, a multi-functional disk, can include several titles in a single disk, and characteristics of contents such as picture resolution, the number of audio channels, and display mode (for example, 4:3, 16:9, Pan-scan, or letter box) may be different according to each title. Therefore, additional information to indicate title characteristics is recorded in a DVD. In addition, a copy-right information, a disk type information on single-sided or double-sided, and various information for providing new functions are recorded in a DVD. This means that the DVD has different characteristics if a contained title is different.
Accordingly, new functions are embodied and new hardware elements are added in a recently developed DVD player in order that reproduction methods or data processing method adequate to the title characteristics and the additional information may be executed without an operation fail  failure.
However, the digital TV 200 connected to the DVD player 100 through a digital interface such as the IEEE 1394 standard may not equip a processing capacity corresponding to the data processing capacity and the operation features of the DVD player 100, and may not support the characteristics of contents of the DVD in which aforementioned additional information and data for new functions are recorded.
Moreover, a low-price digital TV may not have information on its processing capacity and operational features, or may not support the negotiating function for mutual exchange of the feature information. In these case, the digital TV cannot process video/audio data of various characteristics provided by the DVD player 100 appropriately.
Accordingly, the video and audio data normally reproduced from a DVD by the DVD player may be presented abnormally in the digital TV.